Global rupture of a nuclear reactor lower head with elevated temperature due to severe accidents

This paper is concerned with the global rupture of a reactor pressure vesse l (RPV) with elevated temperature due to severe accidents in order to check if the RPV wall can retain the high-elevated pressure. The global rupture of an RPV is simulated by finite element limit analysis for the collapse lo ad and mode to secure the safety criteria of a nuclear reactor under severe accident conditions. Finite element limit analysis is a systematic tool de aling with upper bounding and minimization technique to calculate the colla pse load and mode. The finite element code (CALF, computer analysis of lowe r head failure) developed provides the temperature elevation in the lower h ead of a nuclear reactor under severe accident conditions as well as the co llapse load and mode. The thermal analysis has to deal with heat transfer f rom the debris pool to the RPV wall and the top of the pool. The temperatur e distribution in such a system depends sensitively on the initial temperat ure of the debris pool and the thermal properties of a gap between the debr is crust and the RPV wall. For accurate calculation, the thermal properties of a gap have to be determined in consideration of the gap size and condit ions. (C) 1999 Elsevier Science S.A. All rights reserved.